If the US healthcare system was anywhere near as efficient as the NYC subway, that would be a massive improvement.
I must admit I do not understand a lot about the health industry or how efficient it is. I suspect given all the government regulations in the USA it most likely it is now. My personal experiences with the health care industry has been very positive but I am shielded from the cost as my insurance pay for almost all of it (that is a bad idea as I should have an incentive to rationalize my use of it.) My experience using the MTA has been very negative, I see silly things on a daily basis that would be easily fixed if it was a for profit system. I work in software in NYC and it is well know in the developer space in NYC that working for the MTA is a good route toward a below average pay for a programmer but you will pretty much do nothing everyday. That is typical of union dominated MTA. I am fine with keeping it government controlled because I do not think any private concern would touch it now unless we also roll back decades of regulations as well. But get rid of the unions and keep them out.
The USA has great doctors and delivers very high quality care in many places. But, there is a byzantine system of billing, insurance and regulation. The system skews incentives towards over-providing services, not caring about costs and not paying attention to long-term health outcomes.
You're right that NYC has a broken system of public employment. It has certainly been abused by politicians and corrupt unions for a long time. But, that doesn't mean the system should be totally private. There needs to be large government investment in capital improvements and operating expenses. That would be tricky with a completely private system. Perhaps, MTA could contract out things like computer programming or even most of their salaried positions. In any case, New York needs to stop being corrupt.